Process for making inactive menthol



Patented Sept. 23, 1930 UNITED STATES PATENT, OFFICE KARL SCI-IGLLKOPF, 0F DUSSELDORF-OBEBKASSEL, AND ARTHUR SERINI, OI DUSSEL- DORF-I-IEERDT, GERMANY, ASSIGNORS TO RHEINISCHE iKAMPFER FABRIK GESELL- SCI-IAFT' MIT BESCI'IRA'NKTEB HAFTUNG, OFDUSSELDORF-OBERKASSEL, GERMANY PROCESS non axine INACTIVE MENTHOL No Drawing. Original application filed iune e9, 1927, Serial No. 202,458, and in Germany December 15,

1926. Divided and this application filed. September 20, 1928. Serial No. 307,335.

This application refers to improvements in isomer of the inactive menthol, making it and manuafacture of inactive menthol, and is a division of our copending application Serial No.-202,t58 filed on the 29th dayof June, 1927. The transformation of the solid inactive isomenthol described in our co-pending application may be effected by the action of. ment-liolates of the alkali forming metals at temperatures above lOO degrees centigrade, the solid inactive isomenthol being employed by itself or in admixture with other isomers of inactive menthol and separating the crude inactive menthol from the resulting mixture by physical methods described in the U. S. Patent No. 1,625,771 of April 19th, 1927 for, instance by freezing-outvor fractional distil-' lation, purifying the crude inactive menthol by conversion into esters as described in U. S. Patent No. 1,672,346.

Ewample J.Three parts of metallic dium are dissolved in 100 parts of solid inactive isoment-hol, and'the mixture of isomenthol and sodium isomentholate is heated at 180 degrees Centigrade for about :24 hours. Thereaction product is then driven oil by means of steam. The inactive menthol is separated from the resulting mixture of isomers by freezing out or fractional distillation, and is further purified by way of the esters. The isomeric menthols left from the separation and purification are subjected to further transformation; 7

Example 2.-A mixture of parts of solid inactive isomenthol and 50 parts of a. mixture of liquid isomeric inenthols left over from Example 1, is treatedwith the corresponding sodium mentholates as in Example 1 and the resulting menthols mixture is subjected to further treatment as described therein.

We claim:

1. The process for manufacturing inactive menthol, the racemate of natural menthol, which consists in heating solid inactive isomenthol with mentholates of thealkali form-. ing metals and separating from the reaction product crude inactive menthol.

2. The process for manufacturing inactive menthol, the racemate of natural menthol,

which consists in heating solid inactive isomenthol with mentholates of the alkali form- 111g metals and separating from the reaction product crude inactive menthol by fractional distillation.

3; The process for manufacturing inactive menthol, the racemate of natural menthol which cons1sts 1n heatmgsolid inactive isomenthol mixed with other isomers of inactive menthol, with mentholatesof the alkaliforming metals and separating from the reaction product crude inactlve menthol.

4. The process for manufacturing inactive menthol, the racemate of natural men-' thol, which consists in heating solid inactive isomenthol mixed with other'isomers of in-' active menthol, with mentholates of the alkali forming metals and separating from the reaction product crude inactive menthol by fractional distillation.

. 5. The process for manufacturin g inactive menthol, the racemate of natural menthol.

which consists in heating solid inactive isomenthol with mentholates of the alkali formmenthol, with mentholates of the alkali forming metals andseparating from the reaction product crude inactive menthol by fractional crystallization. i v

In testimonylwhereof we affix our signatures. I r i KARL soI-IoLLKo F;

ARTHUR SERINI. 

